Normally, I know where I stand when it comes to the gender pay gap. Providing flexible work upfront and insisting on equal and enforced parental leave is the best way to end discrimination for both men and women. But when it comes to beating the pay gap in the City, flexible working and parental leave won't solve the problem. We are dealing with a different issue and one that is both more traditional and more international in scope.

It's entirely possible to have both a top-notch City job and a family, but you'll need a partner – man or woman is beside the point – who is willing to stay home and look after the kids. People who want to work their way up to the top jobs in the City are not the same people who want to hold down a 9 to 5.

We must appreciate that there is a greater level of compromise involved in working in some kinds of jobs. The uber-competitive, commission-based jobs in the finance sector serve markets that are always open for business. The payoff that you get in a bonus is generally seen as compensation for the inflexible, long working hours, the stress, and the uncertainty that comes as part of that package. City workers must, by the same token, accept putting off having a family or taking the backseat to their partner when it comes to bringing up the kids. Part of the pay gap may stem from women simply not wanting to make that compromise.

More than in any other sector, women in the City seem to operate in business cultures that regard women as less capable than men. The international nature of the finance sector means that women must deal with sexism beyond our borders. Often women simply cannot be the main contact for a business relationship when the person on the other side of the phone considers it against their custom to work with women. Many overseas trips to regions such as the Middle East are impossible for women to go on alone, meaning that they won't be put forward, or put themselves forward, for the job. Back on home turf, the accepted and expected location of many business meetings is none other than our capital's lap dancing clubs. Many clients request to conduct their meetings in such environments. It's not hard to see how difficult it can be for women to "close deals" in such atmospheres.

We must throw the weight of our opinion behind Harriet Harman and the Equality and Human Rights Commission on this one. Make companies in the City report their pay by gender. Ban secrecy clauses – the idea that you are breaking the law by telling a colleague how much you earn is ludicrous. That will get us some of the way. Then change back the licensing laws for lap dancing clubs.

For now, we should do what we can to stop our own finance sector from discriminating against women. But what we need to do next is figure out what to do about the rest of the world. London's "City" will not be constrained by the rule of British law alone. We have accepted that dealing with bonuses in London also requires dealing with the international bonus culture; we must tackle sexism in the same way.